1973 23ft.seacraft

[CaptMin]

I'd leave the I/O in the boat. The gain in cockpit room is traded out in fishing space off the stern. The boat is designed and balanced for the I/O, and it's easier to work on if you are on the water and have a problem. It's cleaner and more economical. Motor parts can be purchased anywhere, and cheaper.
I have the original chev. straight 6 in my 1967 Seacraft. For the first 15 years, it hung in a sling at a camp year round, and was used 12 months out of the year. It ran at 2 speeds, wide open and stopped. It still has the same alternater on it. I replaced the head and valves on it once at probably 1/6 the cost of a power head on a large OB, and I recall replaceing a fuel pump while sitting comfortably on the deck next to the motor.
It's been on the trailer for the last bunch of years, but a neighbor changed the points, condenser, plugs, coil, and rigged a can for fresh gas, and it startd (about a year ago). No blue smoke, no black smoke, no nothing, and it ran and idled as good as ever.
There might be a safty factor also. I don't know what kind of water you use the boat in, but if you ever get caught in a bad storm or heavy seas, you might be glad that you didn't do anything to alter the balance, and sea worthiness of the
boat.